Scoping out the GigE MAN vendors

New players offer inexpensive, flexible broadband links.

By David Axner
Network World, 09/17/01

If you're looking for an alternative to pricey and inflexible T-1 connections to the Internet, or if you want to build a campus or metropolitan-area network without making a capital investment, one option is a Gigabit Ethernet-based MAN vendor.

Newcomers such as Telseon, Yipes Communications and Cogent Communications are offering inexpensive broadband links that can be provisioned quickly, plus they offer access to value-added services from network service providers, including application hosting, storage services and Web hosting.

They can also connect companies throughout the U.S. or globally over WAN broadband optical links that interconnect MANs. In addition, these vendors are bringing fiber directly to customers within multitenant buildings by connecting to the building's vertical riser. Ethernet is the dominant access method, which enables multitenant building customers to connect directly to their building LAN.

The network design looks like:

Gigabit Ethernet switches aggregate customer traffic and connect to routing switches in the core network using optical lasers over single-mode fiber-optic cable.

SONET, dense wavelength division multiplexing (DWDM) or Gigabit Ethernet runs in the core network. Gigabit switches connect directly to SONET switches through Packet over SONET interfaces for existing SONET installations. (When 10-Gigabit switches become available, they will provide direct SONET connections at OC-192.)

In new installations, vendors are using Gigabit Ethernet switches with optical interfaces in the core network. Trunking (link aggregation) is deployed for switch-to-switch connections for increased bandwidth.

DWDM allows vendors to support multiple channels on a fiber pair. A full-duplex Gigabit Ethernet link requires a fiber pair for each 2G bit/sec channel. DWDM can combine up to 16 channels on a fiber pair, and in the near future, up to 32 channels, which eliminates the need to deploy or purchase multiple fiber pairs.

Coarse WDM (CWDM) supports fewer channels (usually four or eight) that are spaced wider across the WDM frequency spectrum than DWDM, but it is less expensive than DWDM. Some vendors find this option more cost effective.

The players:

Cogent Communications, headquartered in Washington, D.C., targets commercial customer premises in major metropolitan areas nationwide. It addresses users within a multitenant building who need broadband access to the Internet or who need broadband connections to locations within the same metropolitan region or in another city supported by a Cogent MAN. It provides 100M bit/sec access to its network.

Cogent's nationwide network is an end-to-end IP-based network. Its backbone runs at OC-192 (9.952G bit/sec) over fiber and interconnects its MANs in at least 20 U.S. cities. Cogent's MAN rings run at OC-48 (2.488G bit/sec). While Cogent uses long-haul DWDM to interconnect its backbone nodes, it uses CWDM for its MAN rings. Each fiber strand within Cogent's fiber cable supports up to 128 separate channels.

Telseon, based in Palo Alto and Denver, has deployed MANs in 20 major U.S. cities and 60 data centers. While Cogent and Yipes target enterprise customers, Telseon targets service providers, which use the Telseon infrastructure to provide services to enterprise customers.

Telseon's strategy of supporting multiple service on its MANs benefits enterprise users by providing them with a range of services from multiple service providers. They can contract with several service providers for different types of services provided at the same point of presence.

Telseon provides its standard service dubbed Ethernet IP, which is priced on bandwidth and distance; and its other service, called Metro Wave Service, is protocol independent and provides its service-provider customers direct connections between two network locations within a metropolitan area at 2.5G bit/sec and 10G bit/sec over DWDM. This service supports data, voice over IP and Internet traffic. The service provider who contracts Telseon for this service can demux the bandwidth and provide connections via its own access equipment to companies over legacy circuit switching technologies, such as T1/E1 and T3/E3.

Telseon says it negotiates the price of this service on a case-by-case basis. Pricing depends on volume, geographical factors and user requirements. Telseon offers its service provider customers three types of network connections: point-to-point, point-to-multipoint and multipoint-to-multipoint.

Yipes, located in San Francisco, provides broadband LAN-to-LAN interconnect service, called Yipes MAN and Yipes WAN, and a LAN to Internet access service it calls Yipes NET. Yipes' network is IP-based end to end. Yipes MAN is protocol insensitive and can accommodate any Layer 3 protocol. However, Yipes WAN is an IP transport service, which limits traffic to IP protocol. It also restricts transport speed to between 1M bit/sec and 80M bit/sec. Yipes secures its MAN service as a VPN. Its WAN gateway, a VPN device provided by NetScreen Technologies, supports Triple-DES and packet authentication.

Yipes also offers a managed firewall service (Yipes WALL) for its Yipes NET subscribers. Yipes WALL includes a firewall device (rated at 100M bit/sec maximum) from NetScreen configured to a customer's specifications. Yipes installs the firewall at the subscriber site. It includes a firewall monitoring service provided by Yipes partner, Riptech, which provides its Security Operations Center from which security analysts monitor customer firewalls on a 24-7 basis.

Delivering the goods

Cogent subscribers get a dedicated 100M bit/sec Fast Ethernet connection for a flat rate of $1,000 per month. Cogent brings its fiber cable directly to the building at no cost to subscribers, and connects to standard Category 5 risers within the building. At the subscriber's LAN, the Cogent access cable plugs directly into the RJ-45 port on a Fast Ethernet network interface card.

Telseon customers currently average 50M bit/sec of bandwidth for the initial order, but many quickly move up to 70M bit/sec or more. Telseon customers can easily provision their network because it is an Ethernet, IP-based network. A Telseon browser enables users to instantly gain more bandwidth by �a click of their mouse" button. Telseon calls this feature �instant scalability." Telseon customers can scale their bandwidth from 1M bit/sec up to 1G bit/sec in just 10 seconds. Telseon's scalability has a granularity of 1M bit/sec.

Yipes delivers its service to subscribers via a direct fiber connection between its MAN and the customer premise. Like its competition, it connects its service directly to a 10/100Base Ethernet RJ-45 port on the customer's LAN. Yipes subscribers can scale their bandwidth from 1M to 1G bit/sec in 1M-bit/sec increments. But, changing bandwidth is not instantaneous. Customers must contact Yipes with their requested bandwidth change, which is executed by the next day.

The vendors behind the vendors

Cogent's network is Cisco-based. It is constructed around Cisco's ONS 15454 and ONS 15800 Optical Network Switches and its 12016 Gigabit Switch Router (GSR).

Telseon constructs its networks with Gigabit Ethernet switches from Foundry Networks and Riverstone Networks. Foundry's BigIron switches are used in Telseon's core networks located in higher-density cities, while Telseon uses Riverstone service interface units and access switches in all of its networks and Riverstone's core switches in Telseon MANs not supported by Foundry. Extreme, ONI and Cisco are also equipment suppliers to Telseon.

Telseon's core network is optical and uses long-range Gigabit Ethernet Interface converters (GBIC) and DWDM to interconnect switches over single-mode fiber cable. Multiple links interconnect switches and DWDM will eventually support up to 10G bit/sec on each wave, which provides high scalability and redundancy for network resilience.

Telseon has been deploying CWDM technology to scale-up its networks and leverage the use of installed fiber cable. CWDM is more cost-effective in MANs, where fiber cable runs are limited to the metro area, than DWDM equipment designed for long-haul networks. Telseon plans to deploy 10 Gigabit Ethernet switching for its core when it becomes available.

Yipes has several partners that support key components of its network. Yipes partnered with Metromedia Fiber Network to deploy fiber cable in major U.S. cities served by Yipes. Yipes also has partnerships with major IP backbone providers, such as Level 3 Communications and Qwest Communications to transport packets over their WANs between its geographically dispersed MANs. Yipes uses Extreme Networks Summit and Black Diamond switches for its MANs and Juniper M40 routers for its optical network core and M20 routers for differentiated services at the edge.

How to choose

Prospective users of service providers should select a service provider based on the provider's geographical coverage, its growth plans and its service-level agreement (SLA).

A SLA should guarantee successful installation on the date it specifies, the bandwidth and service availability that the customer specifies, and the percentage of network availability, packet latency, and packet-loss delivery specified by the SLA.

Service providers that connect directly to the customer premise eliminate last mile costs for the subscriber and make it easy for subscribers to access their service. Subscribers should be able to immediately upgrade their service bandwidth according to their need, for example, "with a click of their mouse button."

Network availability should be 99% and packet latency should be minimum for packets that conform to the SLA. For example, Telseon claims an average latency of 1.5 msec for its Standard Data Service. Also, packet loss ratio - the number of lost packets divided by the number of transmitted packets - should be less than 0.01%. Telseon rates its rate as 0.004% for its Standard Data Service. The subscriber should also be able to upgrade the SLA according to need. All these objectives need to be met for successful network service.

Axner is president of DAX Associates, a network analyst and consulting firm in the Philadelphia area that produces a Gigabit Ethernet market study called 10 Gigabit Networks. He can be reached at daxner@adelphia.net.